Manufacture of rollers and particularly rollers adapted for use as printing rollers



i which compositions possesses jcertain desirable Patented July 29,v 1930 nAVIn assassins, or meme-1AMRainwater; emmas,r ssie ebn isan; ass;

' I am ss, iir vr'irnni or Lennon, nnana v'n;

senses i Application filedMay131,I1927,Serial so. issjcor-and ni GreatBritainjJune 3, 1926.1

This invention relates to the manufacture of :rollersgaand particularly such as are adapted forusein the-distribution of ink 111 .plfintingiand like operations. and iii-the productionof sheets or slabs or. the like adapted lithographyi and m the for use in R printing, offset process: 7 I a v It is W'el'l known.thatcgelatine; composi-i tions are; commonlyempl'oyed inthe forma tion of -.p'rin-ters rollers,ithat tis to say,the

rollers employed in connection witlrprinting It. w'ould'seem that the surface of gelatine properties in this connection.

Hitherto, in the production of such rollers, the general practice has been to cast a body of a gelatine composition about a metal or wooden mandrel. In the course of use the surface of the gelatine composition becomes injured and it is necessary to recast the roller, that is to say to remove the gelatlne composition from the mandrel and to-form thereon a further body of a like composition. This operation necessitates a certain amount of skill and only in relatively few cases is the operation performed in the printing Works.

Moreover, such gelatine composltions are sensitive to variation in temperature, that is to say a composition which is sufficiently elastic or resilient at a given temperature becomes toohard at a certain lower temperature and too soft or even fluid at a higher temperature. They are in fact gelatine compositions which are :fluidat elevated temperatures but which at the normal tome peratureof the air exist as resilient or elastic masses. f

It has been proposed to employ other materials in forming printing rollers, for instance sulphurized oil compositions, and, further, it has been proposed to provide rollers formed from resilient materials other than gelatine compositions for instance sulphurizecl oils, With a coatlng of a gelatine composition which is simllar to that at present used in forming printers rollers and is as above stated temperature sensitive.

Sulp'hurized oil compositions in many cases exhibit a certain degree of mechanical iwe'akness whichris perhaps best described as shortness. v I a p a a Tllhus bodies of; these compositions 1 when sub1eoted to certain stresses of no great mag Such rollers} are therefiire liable to be in- )IIIGd by the type faces when they aroused for inking type. machines-for inking thefaces'ofthe type or other impression-producingifmeans;

One of the observations "on which the pres;

. :ent invention is based is'that theipjrovi sionon* the surfaces 0f bodies of "compositions; 1 possessing the} before mentiohed properties or character of vulcanizedoil compositions; ofan attentuated coating of a flexible-r: insolubi li'z'ed gelatine composition,- i the resistance thereof {to the" destrilctive ageh cies to i which E they are s'iibj ected when used as inking "rollersf caii be considerably in- The" expression -attenuatetlb coating as used herein denotesgenerzfllyc atiiigs having a thickness *of one-fortieth 'to one fifteerith or on'e-tentlrof a inilli1netre=oreveii more so I long as the coating doesnot by reason of its thickness i the body kccord sions orgelatirre oss ss=ing-both 10w vi s cosity andhigh concentration are' e ployedr" 1 Thus, dispers 'ns of gelatine cohtaining' bo'dies whichdepressthe gelating" point of t he dispersions maybe-used in forming the "coat lngg w the bodies, adapted" to depress thegel'ating' point, which maybe present in the dispersions-used are such thatthey may be removed or changed!" character after t the f clispersion is appliedtothe body to be coated manumdmfina" on noLnnRsYAnn :enn'i ronnnnrynonnnns, 4114mm) non nsii As d p playing a conclioida l' fracture. A: r i

Usually the dispersions used are, of

characterjthat they are .fiuid :atsubstuitia'lly the norm al temperature :of the air or slightly elevated temperaturesr fl Thus;- iii :5: accordance with: I the invention, gelatine compositions, the i hardening or' se't ting of which is to be attributed to the evaporation of the whole or a portion of their content of solvent,may be used.

Alternatively, gelatine compositions, the setting point of which can be raised by treatment with suitable reagents, may be employed. I In a further. alternative, dispersions of gelatine are employed in a sufiiciently heated state to diminish their viscosity to a degree such that *theymaybe applied'to the roller and form thereon an attenuated coating orthin film. a 7

Generally it is found preferable to use high grade gelatines in forming the com ositions but insome cases glues of suita le qualities maybe used. Y

In some, casesirliquid glues will be found suitable.

vPreferably the gelat-ine coating. ishardened by means of formaldehyde or by chro-- mium compounds, the former being used for thispurpose in the formo'f a solution'or as vapour. Y V

After the gelatine coating has set and after I it has been hardened or coagulated the coating istreated to increase its fiexibility, as for instance by impregnating it with glycerine or an equivalent'material employedin theform ofan aqueous solution. h i During thetime the roller is in use the proportion of ,glycerine in the coating may 1 become reduced and the coating thus tend to develop brittleness; theori inal elasticity may in such case be restored y impregnating the coating withiglycerine. a.

A further feature of the invention iscontreatment of a roller with a gelatine composition the treatment may be repeated until a coating of the desired thickness is formed thereon.

While the invention is mainly concerned I with rollers adapted for use as printers rollers it is not confined to rollers for use for any particular purpose; for instance, the invention extends to rollers adapted for use as pressure rollers in connection with dupli-' cating machines and to rollers for use in connection with offset printing machines adapted to perform the function of. the so-called blanket provided in such machines.

Having now described my invention, what I claim as new and desire to secure by Let-.-

ters Patentisz- I The process of producing rollers,-sheets,

slabs and: the like which comprises immersing a suitably: formed body ofa'vulcanized oil composition. in a dispersion of gelatine' which is fluid at temperatures slightly above normal temperature of the air, allowing the excess of gelatine to drain'from said body, subjecting the gelati ne to .the action of an insolubilizing agent and immersing the same .in a hygroscopic softening agent.

In testimony whereof I have signed my name to this specification.

' DAVID GESTETNER.

cerned with the yproduction of ,a' roller pro;

vided with an attenuated coating of a ge1a-- tine composition which has a roughened,

i toothed'or grained surface.

Thus in accordance with this feature of the invention a dispersion'of gelatine may 1 be sprayed on to the'roller eitherbefore or after it has been provided with an attenuated coating of a gelatine composition. 7

Rollers having a roughened surface are particularly suitable for use in connection with offset printing machines and a the grain-t ing of the surface of the roller may come spend withthe graining of the surface of the member of the offset machine from which the oflset'impression is transferred.

The following is an example of a suitable compos tion for use in accordance with the inventionzto parts by weight of gelatine dispersedin 100 parts by weightof a mixture consistingof equal parts byvolume of glacial acetic acid and water.

In carrying the invention into effect the I igelatinecomposition ma be applied to the body ofthe roller by a owing, spraying or immersion operation.

Where a suflicientl thick but sun atten- V uated coating cannot obtained by a single.

ion 

